Research

1. Although in vitro maturation (IVM) of oocytes is an important part of assisted reproduction, the developmental rate of embryos from IVM oocytes is lower than in vivo counterparts. It has been shown that follicle-stimulating hormone (FSH) increase cAMP accumulation oocytes during follicle growth and that an artificial increase of intracellular cAMP before culture significantly improves oocyte developmental competence in cattle and mice. Here, we show that forskolin and 3-isobutyl-1-methylxanthine treatment of prophase-I stage oocytes induced the expression of genes required for glycolysis, fatty acid degradation, and the mitochondrial electron transport system and improved mitochondrial functions and ATP levels in oocytes without involving nuclear maturation. We propose the existence of a comprehensive energy-supply system in oocytes under follicle-stimulating hormone stimulation as a potential explanation of how oocytes acquire developmental competence.

2. It has been shown that disordered diets cause obesity in male mice. Furthermore, obesity and metabolic syndrome have been shown to cause infertility in female mice, and have been shown to impair mitochondrial function in oocytes. To assess the effects of dietary habits on the performance of female mice, we analyzed the effects of food type (regular vs. moderately high calorie diet) and feeding pattern (ad lib vs. time-restricted feeding) combinations on the number of ova and the developmental potential of fertilized ova. We showed that high calorie feeding increased the number of oocytes. On the other hand, time-limitted feeding of normal feed caused a decrease in serum LDL cholesterol and an increase in reactive oxygen species in oocytes, impairing their post-fertilization developmental potential. 

3. Miscarriage and fetal growth reterdation (FGR) cannot be adequately prevented. We evaluated the effects of administration of CTRP6, a human protein that inhibits complement second pathway activation, on miscarriage, fetal and placental development in a mouse model of spontaneous abortion and FGR. We revealed that administration of CTPR6 increased placental and fetal weights. Furthermore, administration of CTRP6 was shown to promote helical artery remodeling.

4. In vitro culture of growing oocytes that do not have the ability to mature, fertilize, or develop embryos is expected to be a new method of oocyte collection, but low viability and developmental potential pf oocytes grew in vitro is a major challenge. We have shown that culturing oocytes in vitro together with mural granulosa cells, which constitute the follicle, maintains oocyte-granulosa cell communication via gap junctionns and improves oocyte viability, development, and post-fertilization development.